ctail — Cross-Platform Log Tail Viewer with Highlighting

ctail — short for color tail — is a desktop log file viewer built with Wails v2 (Go backend + Svelte frontend). Think tail -f, but with regex-powered color highlighting, multiple tabs, and a full GUI. Inspired by BareTail. Supports Windows, Linux, and macOS.

📖 User Manual — Full documentation on features, settings, and usage.

Screenshots

Features

• Multi-tab interface — Open multiple log files simultaneously with keyboard navigation (Ctrl+Tab / Ctrl+Shift+Tab)
• Tab management — Drag-and-drop reordering, rename tabs, color-code tabs, quick toggle between recent tabs
• Real-time tailing — Follow mode streams new lines as they're written, with automatic enable/disable on scroll
• File rotation detection — Automatically detects log file rotation (inode changes) and reloads the new file
• Regex-based highlighting — Rules with foreground/background colors, bold/italic, line-level or match-level matching
• Sliding window buffer — Memory-bounded scrolling through large files; configurable buffer size (default 10,000 lines)
• Profile system — Multiple highlighting profiles with visual rule preview and drag-and-drop reordering
• AI assistant — Ask AI about your logs or auto-generate highlighting rule profiles. Supports GitHub Copilot, GitHub Models, OpenAI, and any OpenAI-compatible server (Ollama, LM Studio, etc.)
• Non-blocking I/O — Files on slow or unreachable network mounts (NFS, CIFS/SMB, SSHFS) won't freeze the UI; all file operations run in the background with timeouts
• Session persistence — Window position/size, open tabs, active profile, and all settings survive restarts
• Recent files — Quick access to recently opened files from the File menu
• Native menu bar — File, Edit, View, Tools, and Help menus with standard keyboard accelerators
• Rich context menus — Right-click tabs for close, rename, color, refresh, change file path, copy path, reveal in file manager; right-click logs for copy/select/AI assist
• VS Code-style search — Ctrl+F opens an inline search bar with case-sensitive, whole-word, and regex toggles, match counter with ↑↓ navigation, and a filter mode that hides non-matching lines
• Check for updates — Automatic and manual update checks from the Help menu
• Themes — 21 built-in color themes (Catppuccin, Nord, Tokyo Night, Gruvbox, Dracula, One Dark, Solarized, Everforest, Ayu, Kanagawa, Matrix, Rosé Pine, Monokai, and more), each with dark and light modes. Supports custom themes via JSON files.
• Display & GPU settings — Configurable display backend (auto-detect, X11, Wayland) and GPU rendering mode on Linux
• Background optimization — Event pausing when the app is hidden and lightweight activity signals for inactive tabs keep the UI responsive
• Cross-platform — Linux, Windows, and macOS

Quick Start

Prerequisites

• Go 1.21+
• Node.js 18+
• Wails CLI v2
• Linux: libgtk-3-dev, libwebkit2gtk-4.1-dev (Ubuntu 24.04+) or libwebkit2gtk-4.0-dev
• Windows: WebView2 (included in Windows 10/11)

Build & Run

# Install Wails CLI
go install github.com/wailsapp/wails/v2/cmd/wails@latest

# Run in dev mode (hot reload)
make dev

# Build for production
make build

# Run tests
make test

Note: On Ubuntu 24.04+ / Zorin OS 18, the webkit2_41 build tag is required (handled automatically by the Makefile). Override with make dev TAGS= on systems with webkit2gtk-4.0.

Install (Linux)

After building, install system-wide with desktop integration:

make build
sudo make install

This installs the binary to /usr/local/bin/, a .desktop file for application launchers, and icons at all standard sizes. Uninstall with sudo make uninstall.

Linux Packages (deb/rpm)

Build .deb or .rpm packages with proper dependencies (libgtk-3-0, libwebkit2gtk-4.1-0):

# Requires nfpm: go install github.com/goreleaser/nfpm/v2/cmd/nfpm@latest
make package-deb    # → build/ctail_<version>_amd64.deb
make package-rpm    # → build/ctail-<version>-1.x86_64.rpm

# Install
sudo dpkg -i build/ctail_*_amd64.deb     # Debian/Ubuntu
sudo rpm -i build/ctail-*-1.x86_64.rpm   # Fedora/RHEL

Architecture

Go Backend                          Svelte Frontend
┌──────────────┐                    ┌──────────────────┐
│ File Tailer  │ ──Wails Events──▶  │ Tab Bar          │
│ (polling,    │                    │ Log View (scroll)│
│  offset idx) │                    │ Highlighted Lines│
├──────────────┤                    ├──────────────────┤
│ Config Mgr   │ ◀──Wails Bind──▶  │ Settings Panel   │
│ (JSON files) │                    │ Rule Editor      │
├──────────────┤                    ├──────────────────┤
│ Rule Engine  │                    │ Highlight Utils  │
│ (regex)      │                    │ (client-side)    │
├──────────────┤                    ├──────────────────┤
│ AI Client    │ ◀──Wails Bind──▶  │ AI Dialog        │
│ (multi-      │                    │ (chat, rules gen)│
│  provider)   │                    │                  │
└──────────────┘                    └──────────────────┘

• Go backend handles file I/O (polling + direct seek via byte offset index), configuration persistence, the rules engine, and AI provider communication
• Svelte frontend handles rendering, client-side highlighting (for instant rule feedback), scroll buffer management, and the AI assistant dialog
• Communication via Wails bindings (sync method calls) and events (async streaming)
• No external Go dependencies beyond Wails itself

Menu Bar

Themes

ctail ships with 21 built-in color themes, each with dark and light modes:

Switch themes in Settings → Theme and toggle between dark/light with View → Toggle Theme.

🎨 Credits: The built-in theme palettes are inspired by and adapted from OpenCode by Anomaly, which provides a wonderful collection of editor color themes. Thank you for making great design accessible to everyone!

Custom Themes

Create your own themes by dropping a JSON file in the themes directory. See the Custom Themes Guide for full documentation, examples, and tips on adapting VS Code themes.

Configuration

Config files are stored in platform-specific directories:

See the User Manual for details on all settings and configuration options.

Keyboard Shortcuts

Known Issues

Multi-monitor maximize on Wayland (Linux)

On Wayland with multiple monitors of different resolutions, the maximize button may use the wrong monitor's dimensions. This is an upstream limitation in GTK/WebKit2GTK affecting all Wails v2 apps. ctail includes a workaround that detects and corrects wrong maximize dimensions, but it may not work in all configurations.

Command-Line Flags (Linux)

These can also be configured persistently in Settings → Display Backend and Settings → GPU Rendering.

License

MIT